Integrated circuit (IC) fabrication often involves formation of metal-containing materials over semiconductor substrates. Such formation may utilize a deposition process such as, for example, one or more of atomic layer deposition (ALD), chemical vapor deposition (CVD) and physical vapor deposition (PVD).
A metal-containing material is any material that comprises “metal.” The elements of the periodic table may be classified as being either metals or nonmetals on the basis of their general physical and chemical properties. However, a few elements have intermediate properties, and these elements are sometimes classified as metalloids. The metalloids include boron, silicon, germanium, arsenic, antimony, tellurium and polonium. The term “metal” is utilized herein and in the claims that follow to refer to any element that would not be classified as a “nonmetal”, and thus includes metalloids as well as regular metals.
The metal-containing materials incorporated into ICs may be utilized in any of numerous devices and structures. For instance, the metal-containing materials may be utilized for electrically conductive structures (for instance, conductive regions of wordlines, bitlines, and other lines; electrodes of capacitors; bond pads; etc.), and/or for phase change materials (for instance, mixtures of germanium, antimony and tellurium may be utilized to form phase change materials).
The properties of metal-containing materials may be altered by the purity of the metal-containing materials, and often desired electrical properties are better achieved with high purity metal-containing materials than with lower purity metal-containing materials. Also, it can be easier to maintain consistency amongst a plurality of devices if the metal-containing materials are of high purity than if the metal-containing materials are of lower purity, since the types and amounts of impurities within the lower purity metal-containing materials may fluctuate—which may lead to differences in electrical properties amongst the devices.
One method of forming metals is to utilize metal amidinates and ammonia in ALD processes. For instance, germanium may be deposited utilizing sequential pulses of germanium amidinate [such as, for example, bis (N,N′-diisopropyl-butylamidinate)-N-germanium (II)], and ammonia. However, the layers formed by such deposition may contain high levels of carbon and nitrogen contamination; with example high levels of carbon and nitrogen contamination being about eight atomic percent and about five atomic percent, respectively.
Another method of forming metals to utilize formic acid to reduce metal amidinates during CVD processes. For instance, copper amidinate may be reduced by formic acid during a CVD process to form a copper deposit. It is believed that the copper acts as a catalyst during the CVD process to form monatomic hydrogen from the catalytic decomposition of formic acid, and that such hydrogen then reduces the amidinate to form the copper deposit.
Although the formic acid CVD processes work with some metal amidinates, there are other metal amidinates that lack the ability to self-catalyze formation of hydrogen from formic acid, and that accordingly are not suitable for utilization in the formic acid CVD processes.
It is desired to develop new methods of forming metal-containing materials suitable for utilization in integrated circuitry.